1. Field of the Disclosure
The present disclosure relates to a MIMO communication method that uses MIMO (multiple-input and multiple-output communication), and to a MIMO transmitting device and a MIMO receiving device.
2. Description of Related Art
A MIMO communication scheme has been put into practical use as a technology for increasing communication capacity. This technology is designed to allow different data sequences on N systems to be transmitted using a transmitter having N transmitting units and a receiver having N receiving units, where N is an integer greater than or equal to 2, and reserves a communication capacity that is N times, resulting in a communication speed that is N times, that in the case of transmission on only one system.
This technology is currently used in LTE (Long Term Evolution), WiFi (Wireless Fidelity), and the like as SU-MIMO (Single User-MIMO). In the future, an extended version will be available as MU-MIMO (Multi User MIMO), and studies on improved frequency utilization efficiency with the use of orthogonality between channels, unified operation of a plurality of cells, and so forth are being intensively made.
In MIMO, currently, as described above, a transmitter and a receiver require individually N transmitting units and N receiving units. That is, a transmitter includes N transmit antennas and N transmit circuits, and a receiver includes N receive antennas and N receive circuits. The N transmit circuits have the same characteristics and the N receive circuits have the same characteristics.
The conditions under which MIMO communication is established are the ability to separate transmit signals by measuring on the receiver side the gain of communication channels of communication paths formed between transmit and receive antennas by using a reference signal transmitted from the transmitter, representing the gain as a communication path matrix (H-matrix) in the form of a matrix, and multiplying the inverse matrix of the communication path matrix on the receiver side.